Amperometric Miniaturised Portable Enzymatic Nanobiosensor for the Ultrasensitive Analysis of a Prostate Cancer Biomarker

Screen-printing technology is a game changer in many fields including electrochemical biosensing. Two-dimensional nanomaterial MXene Ti3C2Tx was integrated as a nanoplatform to immobilise enzyme sarcosine oxidase (SOx) onto the interface of screen-printed carbon electrodes (SPCEs). A miniaturised, portable, and cost-effective nanobiosensor was constructed using chitosan as a biocompatible glue for the ultrasensitive detection of prostate cancer biomarker sarcosine. The fabricated device was characterised with energy-dispersive X-ray spectroscopy (EDX), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Sarcosine was detected indirectly via the amperometric detection of H2O2 formed during enzymatic reaction. The nanobiosensor could detect sarcosine down to 7.0 nM with a maximal peak current output at 4.10 +/- 0.35 x 10(-5) A using only 100 mu L of a sample per measurement. The assay run in 100 mu L of an electrolyte showed the first linear calibration curve in a concentration window of up to 5 mu M with a slope of 2.86 mu A center dot mu M-1, and the second linear calibration curve in the range of 5-50 mu M with a slope of 0.32 +/- 0.01 mu A center dot mu M-1 (R-2 = 0.992). The device provided a high recovery index of 92.5% when measuring an analyte spiked into artificial urine, and could be used for detection of sarcosine in urine for at least a period of 5 weeks after the preparation.

Automated summary

Screen-printing technology is used to immobilize enzyme sarcosine oxidase (SOx) onto screen-printed carbon electrodes, creating a portable nanobiosensor for ultrasensitive detection of prostate cancer biomarker sarcosine. The nanobiosensor shows a high detection sensitivity of 7.0 nM using minimal sample volume and exhibits linear calibration curves in the concentration range of 5 nM to 50 μM. The device has a high recovery index and can be used for detection of sarcosine in urine for at least a period of 5 weeks.